
import { Renderer, Camera, Transform, Texture, Program, Geometry, Mesh } from '../../';

const vertex = /* glsl */ `
            precision highp float;
            precision highp int;

            attribute vec2 uv;
            attribute vec3 position;

            // Add instanced attributes just like any attribute
            attribute vec3 offset;
            attribute vec3 random;

            uniform mat4 modelViewMatrix;
            uniform mat4 projectionMatrix;
            uniform float uTime;

            varying vec2 vUv;
            varying vec3 vNormal;

            void rotate2d(inout vec2 v, float a){
                mat2 m = mat2(cos(a), -sin(a), sin(a),  cos(a));
                v = m * v;
            }

            void main() {
                vUv = uv;
                
                // copy position so that we can modify the instances
                vec3 pos = position;
                
                // scale first
                pos *= 0.9 + random.y * 0.2;
                
                // rotate around y axis
                rotate2d(pos.xz, random.x * 6.28 + 4.0 * uTime * (random.y - 0.5));
                
                // rotate around x axis just to add some extra variation
                rotate2d(pos.zy, random.z * 0.5 * sin(uTime * random.x + random.z * 3.14));
                
                pos += offset;
                
                gl_Position = projectionMatrix * modelViewMatrix * vec4(pos, 1.0);;
            }
        `;

const fragment = /* glsl */ `
            precision highp float;
            precision highp int;

            uniform float uTime;
            uniform sampler2D tMap;

            varying vec2 vUv;

            void main() {
                vec3 tex = texture2D(tMap, vUv).rgb;
                
                gl_FragColor.rgb = tex;
                gl_FragColor.a = 1.0;
            }
        `;

const renderer = new Renderer({ dpr: 2 });
const gl = renderer.gl;
document.body.appendChild(gl.canvas);
gl.clearColor(1, 1, 1, 1);

const camera = new Camera(gl, { fov: 15 });
camera.position.z = 15;

function resize() {
    renderer.setSize(window.innerWidth, window.innerHeight);
    camera.perspective({ aspect: gl.canvas.width / gl.canvas.height });
}
window.addEventListener('resize', resize, false);
resize();

const scene = new Transform();

const texture = new Texture(gl);
const img = new Image();
img.onload = () => texture.image = img;
img.src = 'assets/acorn.jpg';

const program = new Program(gl, {
    vertex,
    fragment,
    uniforms: {
        uTime: { value: 0 },
        tMap: { value: texture },
    },
});

let mesh;
loadModel();
async function loadModel() {
    const data = await (await fetch(`assets/acorn.json`)).json();

    const num = 20;

    let offset = new Float32Array(num * 3);
    let random = new Float32Array(num * 3);
    for (let i = 0; i < num; i++) {
        offset.set([
            Math.random() * 2 - 1,
            Math.random() * 2 - 1,
            Math.random() * 2 - 1,
        ], i * 3);

        // unique random values are always handy for instances.
        // Here they will be used for rotation, scale and movement.
        random.set([Math.random(), Math.random(), Math.random()], i * 3);
    }

    const geometry = new Geometry(gl, {
        position: { size: 3, data: new Float32Array(data.position) },
        uv: { size: 2, data: new Float32Array(data.uv) },
        normal: { size: 3, data: new Float32Array(data.normal) },

        // simply add the 'instanced' property to flag as an instanced attribute.
        // set the value as the divisor number
        offset: { instanced: 1, size: 3, data: offset },
        random: { instanced: 1, size: 3, data: random },
    });

    mesh = new Mesh(gl, { geometry, program });
    mesh.setParent(scene);
}

requestAnimationFrame(update);
function update(t) {
    requestAnimationFrame(update);

    if (mesh) mesh.rotation.y -= 0.005;
    program.uniforms.uTime.value = t * 0.001;
    renderer.render({ scene, camera });
}


document.getElementsByClassName('Info')[0].innerHTML = 'Instancing. Model by Google Poly';
document.title = 'OGL • Instancing';